Grunion stores a history of submissions in a "Feedback" custom post type.
Grunion is short-code-able, not just widget-able.
Grunion can specify a different TO address per form (one of the shortcode parameters).
I'm not certain if Grunion allows sending to multiple recipients. But I don't see that WPMU DEV's does either.
Grunion Ajax (http://wordpress.org/extend/plugins/grunion-ajax/) supposedly enables "instant submission" (no page reload). Does WPMU DEV's have that too?